This invention relates to emission control systems and more particularly to an emission control system for a casthouse.
The Environmental Protection Agency has issued standards for the control of emissions from industrial plants. One of the plants that has been affected by these standards is the casthouse employed in the making of pig iron. A casthouse contains a blast furnace and a plurality of channels, runners and troughs through which the iron and slag that is tapped from the blast furnace is separated and delivered to iron and slag ladles. The iron in the iron ladles called pugh ladles is then taken to basic oxygen furnaces where it is converted to steel. The slag in the slag ladles is taken to the slag pits for land fill.
As the slag and pig iron mixture is tapped from the blast furnace there is a great amount of smoke containing silicon oxide, graphite, iron oxides, particulates, heat and other pollutants that is released into the ambient air from the mixture. This smoke continues to escape into the air from the slag and pig iron as they are channeled by the troughs into their respective ladles. Prior to the E.P.A. standards this smoke filled the casthouse and escaped into the atmosphere. However, this is now unacceptable and some systems exist for limiting and controlling the amounts of smoke and pollutants that are released into the ambient air.
One system basically covered all of the troughs and channels and thus turned them into tunnels. This prevented the smoke from exiting into the casthouse. However the emissions were not caught or treated. At the end of the tunnel whatever emissions had not cooled were released into the air. A further difficulty with the tunnel system is that it did not provide for the viewing of the pig iron and slag as it exited from the furnace. Being able to see the mixture as it came out of the furnace provides for a simple and efficient method to determine whether the cast is good.
Another system for controlling the emissions is using what is called a "bag" house. In this system arched covers are placed over all of the troughs. This entire network of tunnels is then evacuated by pipes connected to the covers. The system uses large fans of about 1000 horse power and roughly 250,000 cubic feet per minute capacity to evacuate all smoke from all of the tunnels. This is then transferred from the side of the arched covers and down into underfloor ducts where it is transferred to a "bag house". A bag house is a large structure containing "bags" through which the smoke is passed and cleaned.